... self-propulsion.

I can't remember the last time I mowed the lawn so many times in one summer. I have a callous on my right hand under my anniversary ring because I keep forgetting to take it off. But we have the best mower! It's self propelled and just turns to start (well, when the battery is charged) and I even know where the gas goes. The self-propelled engine is great... you don't mow the lawn so much as just point the mower in the right direction, and hang on downhill.